MUSEUM OF COMPARATIVE ZOOLOGY. 277 



Family? ADKOUlUDiE. 

 Genus SKPAKATISTA Gray. 



Section IIALOCEIIAS Dall. 



Separatista (Haloceras) cingulata (Verrill) Dall. 



Cithna cingulata Verrill, Trans. Conn. Acad., VI. p. 184, pi. xxxii. fig. 7, May, 1884. 



Habitat. Off Nantucket Shoals and George's Bank, on the coast of New 

 En;4land, and 120 miles S. E. from Delaware Bay, in 906 to 1497 fms., sand 

 and mud, at U. S. Fish Commission Stations 2043, 2076, 2084, and 2733, 

 temperature 38°.0 F. 



Cithna cingulata Verrill was described, and. figured from an immature 

 specimen. The adult shell has the form of Separatista, is flattened on the 

 upper surface of the whorls, and has a strongly bicarinate periphery, so 

 that the spire is scalar, ending in a dark brown dextral larval shell originally 

 furnished with a spirally fringed epidermis. This nucleus is smooth, but the 

 rest of the shell is strongly spirally grooved, aud covered with a light rather 

 fugacious epidermis. 



I was unable to extract the animal without destroying the only perfect speci- 

 men, but it was of a dark reddish color, and bore a very remarkable operculum 

 of a subtriangular shape not unlike that of Xenophora, but laterally elongated, 

 and at the small end of the triangle, which, in the retracted state, is close to 

 the columella, there is a small spiral portion of about 2^ whorls. The general 

 outline is that of a half-open fan rising from a small circle. The exterior of 

 the operculum is roughly lamellose and of a dull brown, like the operculum 

 of Baccinum, but less horny and thinner. The only operculum at all similar 

 which I remember is that of Atlanta, which, however, is ovate, smooth, pellucid, 

 and dextral. There are certain points about the shell and opercle which recall 

 Bolium and Persona. The shell is holostomate with the base prolonged at its 

 inner lower angle. The whorls are coiled almost as in Scala. The umbilicus 

 is small but deep. An examination of the type of Separatista in the British 

 Museum shows that, so far as the shell is concerned, its earlier whorls are not 

 dissimilar to our shell. The latter has the last whorl not separated from its 

 predecessor, but I doubt if this character is of generic value. Delphinula laxa 

 Say, referred by Adams to this genus, is doubtless, as suggested by Say, a de- 

 formed Lunatia. In view of the conchological differences and our ignorance 

 of the operculum and soft parts of the original Separatista, I feel justified in 

 proposing a new sectional name for it, as it has nothing to do with Cithna 

 properly so called. For the future, then, it may be termed Separatista 

 (Haloceras^ cingulata (Verr.) Dall. 



